                                                    Ext.onReady(function(){  
        // shorthand  
        var Tree = Ext.tree;  
          
        var tree = new Tree.TreePanel('tree-div', {  
            animate:true,   
            loader: new Tree.TreeLoader({dataUrl:'http://localhost:3000/admin/category/category_tree'}), //修改这里  
            enableDD:true,  
            containerScroll: true  
       });  
     
       // set the root node  
       var root = new Tree.AsyncTreeNode({  
           text: 'Ext JS',  
           draggable:false,  
           id:'source'  
       });  
       tree.setRootNode(root);  
     
       // render the tree  
       tree.render();  
       root.expand();  
   });  